Spinneret assembly for spinning highly viscous polymeric substances



April 22, 1969 R. UIJTERS 3,439,382

` SPINNERET ASSE VISCQUS P MB SPINN HIGHLY OLYME SUBST `ES 1 1 1 l 1 l l 11 INVENTOR. ROBERT SLUIJTEiRS April 22, 1969 Filed Dec. 23. 1966 R. SLUIJTERS sheet 2 ora o o o o o 0 f 33 32 O O O 0 0 o 0 0 Q INVENTOR.

ROBERT SLU l JTRS United States Patent O 3,439,382 SPINNERET ASSEMBLY FR SPINNING HIGHLY VISCOUS POLYMERIC SUBSTAN CES Robert Sluijters, Arnhem, Netherlands, assignor to American Enka Corporation, Erika, N.C., a corporation of Delaware Filed Dec. 23, 1966, Ser. No. 604,293 Claims priority, application Netherlands, Jan. 4, 1966, 6600025 Int. Cl. D01d 1/00 U.S. Cl. 18--8 3 Claims ABSTRACT 0F THE DISCLOSURE A spinneret assembly for the manufacture of filaments, fibers and yarns is provided with more effective means for spinning highly viscous polymers and comprises a main polymer inlet surrounded by a heating chamber in fluid flow communication with a plurality of shape imparting orifices in a spinneret plate; the orifices in the plate are connected to the main inlet by a plurality of connecting conduits or bores of lesser diameter than the said main polymer inlet and the conduits extend throughout the plate substantially parallel to its face.

This invention relates to a novel spinneret assembly for the manufacture of threads by a melt spinning process; more particularly, the invention relates to an improved spinneret plate of a type which is provided with a plurality of orifices and wherein each orifice is provided with an inlet of increased diameter immediately preceding a shape imparting outlet portion of the orifice.

It is well known in spinneret plates that having an orifice with an enlarged inlet immediately preceding a shape imparting outlet has a favorable influence on the spinning materials such as viscose, acetate, and high molecular weight synthetic linear polymers, eg., polyesters and nylon. This enlarged cavity in the plate (at the end opposite that 'which the material is extruded) makes it possible to obtain shape imparting outlets with a smaller diameter. The spinneret plate is so positioned that at least its topmost planar surface (with the inlets) serves as the bottom of a larger chamber (adapted to be constantly filled with molten material) to enable the molten material to constantly fiow through all the orifices and, accordingly, the shape imparting outlets.

In order to produce synthetic filaments, fibers and yarns having improved properties, in most cases it has been found necessary to use polymer having extremely high melt viscosities. Spinneret plates now known and which generally embrace the above construction are unsatisfactory for such high viscosity polymer. For example when spinning polycondensation products, such as polyester, having a very high melt viscosity it is necessary to force the polymer through the assembly under very high pressures, i.e., pressures that are considerably higher than those previously used. Pressures of the order of 1000 atmospheres or higher are not uncommon in spinneret assemblies and it has now been found that various components of known assemblies cannot be subjected to such high pressures. In most cases it is impractical to increase the size or thickness of the various componets, for example, spinneret plates, in order to compensate for the increased pressures now found when high viscosity polymer is used.

For example, in order to prevent deformation of the part of the spinneret plate between the relatively long shape imparting orifices, it would be necessary to substantially decrease the number of orifices provided in an ice individual plate. As will be appreciated, this is not practical from an engineering and a commercial production standpont.

Known spinneret plates also require a relatively large amount of molten material to cover the upper surface of the spinneret plate, which of course increases the residence time of the molten material in the assembly. In view of the high temperatures required for a melt spinning process, this causes degradation of the molten polymeric material. Perhaps more importantly, it has been found that maintaining a uniform temperature of the molten material over the entire surface of the plate is very difficult indeed.

It is therefore the object of this invention to provide an improved spinneret assembly for spinning filaments, fibers and yarn wherein high polymer pressures are encountered.

With construction according to the invention, a spinneret plate is provided with enlarged molten polymer orifices that are connected to a system of branching or connecting channels provided inside the plate and which are substantially parallel to the face` of the plate. The system is then, in turn, connected to at least one main feed inlet for the polymeric material.

Such structure permits the main feed inletfs) for the plate to be in direct communication to a pumping system for polymer abeinlg introduced to the assembly. By means of the connecting channels provided within the spinneret plate, the molten material supplied through the main feed inlet is then distributed over the orifices and, in which case, the plate no longer serves as the bottom of a pressurized chamber and it need only be of a thickness which is sufficient to resist the forces acting in the channels. The diameter of the connecting channels need only to be sufficiently large to obtain a uniform distribution Of the molten material through the orifices.

For a channel into which at one end a molten material is fed and to which there are connected five orifices that are spaced at 5 mm. intervals and have a narrow portion (0.4 mm. in length and 0.25 mm. in diameter), a diameter -of 2 mm. is sufficient to keep the difference in output between the orifices that are farthest apart within the limits that are permissible for manufacture of a uniform yarn.

As a result, the spinneret plate according to the inventi-on is quite suitable in spinning polymer when under very high pressure. Polycondensation products having high melt viscosities which are of the order of 30,000 poises or higher can be utilized with ease. Because of the small capacity of the channels, the residence time of the molten material therein is short, so that the risk of degradation of the molten polymer is eliminated-notwithstanding the fact that the absence of molten material on the upper surface of the spinneret plate makes it possible to maintain the plate at a uniform temperature by merely passing a stream of a heating medium over the upper surface of the spinneret plate.

In a preferred embodiment of a melt spinning assembly according to the invention, the spinneret plate forms a wall; more particularly, a bottom of a chamber through which a heating medium is passed and in which a filter for the molten material is provided between a pumping system of the melt spinning apparatus and the spinneret plate. The orifices, with enlarged inlets, are preferably formed partly by bores perpendicular to the upper surface of the spinneret plate. They are drilled only through part of the plate and have a diameter of a size normally required for enlarged inlets. They further define a narrower bore through the remainder of the plate. The bores on the side of the wide portion are blanked off.

The channels of the system are preferably formed by bores which are blanked off at both ends.

The spinneret plate, and the housing therefor may either be circular or rectangular.

When constructed according to the invention, the plate has been found particularly suitable to be adapted to manufacture of heterogeneous filaments or fibers, viz, those filaments obtained by spinning at lea-st two different molten materials in side-by-side arrangement. To this end, and as a preferred embodiment, the orifices in the plate are arranged in rows with each row being positioned between two main channels. A different molten material may be passed through each channel. As an example, a molten polyamide may be extruded through one channel While ypolyester is extruded through the remaining channel. By means of side-channels, each of the orifices is connected to the two main channels so that the two molten materials may simultaneously be extruded through each orifice.

It should be noted that an apparatus for the manufacture of filaments in which the material to be spun is distributed over the orifices by means of a channel system has been proposed before in U.S. Patent 3,176,346.

The apparatus found in the patent comprises a spinneret block used for the manufacture from spinning solutions of heterogeneous filaments and fibers in which the spinning solutions are supplied through wide main channels inside the block to wide side-channels provided perpendicular to the main channels. The solutions are then distributed over the orifices by means of peripheral grooves in cylindrical inserts located in the side channels.

The proposed construction of the patent does not provide orifices with enlarged inlets which favorably infiuence the spinning process. Moreover, the patented apparatus does not lend itself to spinning molten material under very high pressures. The high pressures prevailing in the wide channels will deform the apparatus.

For a better understanding of the invention, reference is made to the accompanying drawings in which the figures illustrate diagrammatically the several embodiments of apparatus for use in the practice of the invention.

FIGURE 1 shows the lower part of a melt spinning assembly in vertical section;

FIGURE 2 shows the spinneret plate of the melt spinning assembly of FIGURE 1 in horizontal section along the line II-II of FIGURE 1; and

FIGURE 3 represents a horizontal section 0f a spinneret plate for the manufacture of heterogeneous filaments, fibers and yarns.

In FIGURE 1 the numeral 1 refers to an assembly housing, in the bottom pa-rt of which there is provided a cylindrical chamber 2 for receiving a circular spinneret plate 3 above which there is provided a cylindrical chamber 4. Chamber 4 is in direct communication with the chamber 2 containing a filter element 5. Spinneret plate 3 rests on an inwardly projecting rim 6 of a fiange 7 secured to the housing 1 by means of bolts 8.

By means of a sealing ring 9 (provided in an annular recess 10 in the inner wall of the cylindrical chamber 2) there is Obtained a liquid-tight seal between flange 7 and housing 1.

Filter assembly 5, resting on spinneret plate 3, is made up of two adjoining dish-shaped members 11 and 12 between which there is provided a filter material 13. Filter 13 is supported by studs 14 on a conically sloping bottom 15 of the dish-shaped member 12.

Through openings 16 and 17 in the two dish-shaped members 11 and 12, the molten material supplied through channel 18 by means of a spinning pump (not shown) is then fed through filter material 13 to an inlet opening 19 in plate 3.

Through channel 20 (inthe side Wall of the hou-sing 1) there is supplied a heating medium which iiows over the upper surface of plate 3. The medium passes upwards through grooves 21 provided in the wall of the cylindrical chamber 4, and is then discharged via channels 22 provided in housing 1.

Perpendicular to the fiat surface of plate 3 there are provided bores 23, which are not drilled all through the plate. From bores 23 and accurately coaxial therewith there are provided narrower bores 24 which are drilled completely through to the bottom of the plate. The top ends of the bores 23 are closed off utilizing screw plugs 25. Bores 23, which serve as enlarged inlets of the orifices, communicate with the inlet opening 19 by means of a system of branched channels 26 drilled parallel to the flat surface of plate 3. Channels 26 are, at both ends, closed off with screw plugs 27.

FIGURE 2 shows branched channels 26 in plate 3 of FIGURE 1 through which the orifices 24 with their enlarged inlets 3 are connected to the inlet opening 19.

FIGURE 3 shows the positions of the spinning orifices relative to the channels provided in a rectangular spinneret plate, and which is adapted to the manufacture of heterogeneous filaments, fibers and yarns. Orifices 28 are aranged in rows, each row being positioned between on the one side a main channel 29 to which is fed a molten material from an inlet opening 31 and via feed channel 30 which communicates with the main channels 29, Iand on the other side a main channel 32 to which there is fed a different molten material from an inlet opening 34 via a feed channel 33. Channel 33 communicates with the main channel 32. Each of the orifices 28 is with its enlraged inlet opening 35 connected to the two main channels 29 and 32 by means of side-channel 36.

Since the spinning assembly allows of many different embodiments without departing from the -scope of the invention, it will be obvious that the invention is not limited to those above-described.

What is claimed is:

1. A spinneret assembly for producing filaments, fibers and yarns comprising:

(a) a housing,

(b) a filter means within said housing,

(c) supporting means for said filter,

(d) a main polymer inlet means passing through said supporting means and coaxially aligned with said filter means,

(e) a heating chamber within said housing which substantially surrounds said filter supporting means,

(f) said main polymer inlet means disposed in and passing substantially through a spinneret plate mounted below said filter supporting means,

(g) said spinneret plate having a plurality of tubular shape imparting orifices therein,

(h) said tubular shape imparting orifices being in fiuid flow communication with said main polymer inlet means solely through a system of tubular connecting channels of lesser diameter than said main polymer inlet means, and

(i) said tubular connecting channels being substantially parallel to the face of the spinneret plate.

2. A spinneret assembly according to claim 1 wherein the shape imparting orifices are closed off at their uppermost ends.

3. A melt spinning apparatus according to claim 1, wherein the spinneret plate forms at least one wall of said heating chamber.

References Cited UNITED STATES PATENTS 2,784,843 3/1957 Braunli-ch. 3,081,490 3/ 1963 Heynen et al. 3,121,254 2/1964 Heynen et al. 3,341,891 9/1967 Shimizu et al. .3,346,915 10/ 1967 Fleischer et al.

FOREIGN PATENTS 1,377,214 1964 France.

WILLIAM J. STEPHENSON, Primary Examiner. 

